Tar-like undercoating on 63 Valiant...any way to remove it?

If it's cold, the air chisel with a wide blade works really good, like in post #6. It's way faster than any other method i've tried. Otherwise, like above, a torch and a steel putty knife will work. It actually works better when you have two people. One heating with the torch turned way up, and the other one following along scraping.